Educational device



y 1933- I E. G. PLASTERER 1,912,094

EDUCATIONAL DEVICE Filed May '7, 1952 2 Sheets-Sheet l y 1933- E. G.PLASTERER 1,912,094

EDUCATIONAL DEVICE Filed May 7, 1952 2 Sheets-Sheet 2 7 mmmm PatentedMay 30, 1933 EIFFEL GRAY PLASTERER, OF HUNTINGTON, INDIANA EDUCATIONALDEVICE Application filed May 7, 1932. Serial No. 609,942.

The present invention relates to educational devices, more especially toa pendulum capable of demonstrating certain laws of physics orgravitation, and has for one of its principal objects to provide adevice particularly useful in physical investigations for me chanically.and graphically illustrating the principle of the pendulum.

Another important object of the invention 1 resides in the provision ofa device adapted to illustrate the effect of length on the time ofoscillation, and for this purpose, the invention aims to provide apendulum having means whereby the oscillations may be controlled,

thus demonstrating that a pendulum having infinite length would haveinfinite time oscillation.

It is alsoan object of the invention to provide a device by which aweight or vbob is caused by gravity to vibrate through arcs having radiiof any length.

Other important objects and advantages of the invention will be in partobvious and in part pointed out hereinafter.

In order that the invention and its mode of operation may be readilyunderstood by those persons skilled in the art, I have in theaccompanying drawings and in the detailed description based thereuponset out possible embodiments of the same.

In these drawings:

Figure 1 is a front elevation of the device;

Figure 2 is a side elevation of the same;

Figure 3 is an enlarged detail showing the construction of theadjustable guide feature of the device; 1

Figure 4 is a schematic representation of a modification of the device;

Figure 5 is a similar showing of a further modification;

Figure 6 is a diagram illustrating the motion of the infinity pendulum,and

Figure 7 is also a diagram illustrating the various actions of thependulum caused'by the variable adjustment of the parts thereof.

Having more particular reference to the drawings wherein like charactersofreference will designate corresponding parts throughout, my improveddevice may be stated to comprise a table frame 1 having a pair offrontlegs 2and back legs 8, each of the latter being provided at itsupper end with a horizontalcbar connected to the lntermediate portion ofthe front legs 2. These front legs 2 are formed at theirupper end with atransversal connecting bar'5vto which are secured a pair of upwardlyextending and converging'rods 6.

Fixed to the rearward portion of the hori zontal bars 4 adjacent theback legs 3, is a board of the like 7, extending transversely of thetable frame 1. Mounted upon said board 7 is a generally invertedL-shaped support 8 having its lower portion bent upon itself to form abrace-9. The upper portion 10 of the inverted L-shaped support 9 engagesthe free ends of the converging rods 6 by means of a plate ll fixingsaid freeends of the rods 6. In this manner, it will be understood, thatthe inverted 'L-shaped support 8 may be rigidly maintained in itsposition on the frame. I

Also mounted upon the board 7 forwardly of the support 8, is a u shapedbracket 12 wherein is pivoted a lever arm 13, by means of ananti-friction fulcrum bearing 14. The free extremity of the lever arm 13is likewise formed with a frictionless bearing 15 sup- ;portlng arotatable stub shaft 16 rigidly secured to the intermediate portion of apendulum 17 provided at its lower end with an adjustable bob 18.

Associated with the pendulum 17, isa guide clamp 19 capable ofadjustment at various points along the pendulum 17, and carrying a guideroller 20 movable between the pair of vertical and paralleling guiderods 21 disposed forwardly of the pendulum 17 and supported between theupper portion 10 of the inverted L-shaped support 8 and the connectingbar 5 of the frame 1. The guide rods 21 are.preferablyconnected to saidsupport and frame by means of screw threaded shanks 22, whereby saidguide rods may be relatively adjusted to accommodate-the guide roller20. Y

In Figures 4 and 5of-the drawings, I have 7 schematically shown modifiedconstructions of the device, whereby the use of a guide roller will beobtained and guide rods may be dispensed with. In the arrangementparticularly represented in Figure l, the pendulum 17 provided with thebob 18 and carried by the pivoted lever arm 13, is associated with anadjustable clamp 19 connected to one end of a relatively short wire orcable 21 and of a relatively long wire or cable 22. The free end. of therelatively short wire or cable 21 is connected to a suitable supportthrough the medium of a spring 23, whereas the free end of therelatively long wire or cable 22 is connected directly to anothersuitable support.

In the arrangement illustrated in Figure 5, the clamp 19 adjustable onthe pendulum 17, is connected to a sectional rod 2e adjustablein lengthby means of a turnbuckle 25 or the like, and having its free extremityconnected for variable adjustment on a suitable support. The operationand use of my improved device will be best understood by referringto thediagrams shown in Figures 6 and 7 of the drawings, wherein the referencecharacter E corresponds to the pivoted lever; A indicates the pivotal.oint of said arm; 0 the connecting point 0 the arm to the pendulum; Fthe portion of the pendulum between the connecting point 0 and theadjustable guide clamp which is represented in the diagrams by thereference character 0; and, G the portion of the pendulum between theconnecting point 0 and the bob, the latter being designated by thecharacter B.

Figure 6 represents a schematic diagram of the motion of the infinitypendulum, wherein the arm E is supported on the pivot point A. and thearms F and G are supported by the fulcrum O. Thepoint C slidingvertically in the guide identified by the reference character 21 inFigures 1 and 2 of the drawings. As will appear from this diagram, themotion of the pendulum B is in a true horizontal line. The lengths ofthe arms E, F andG being equal, the angular relation must vary in exactratio, that is to say, any increase in the angular relation of E to thehorizontal, must cause a corresponding increase in the angular relationbetween the horizontal and G in exactly the same degree. It will be thusunderstood, that the pendulum B moves in a straight horizontal line andwill remain in whatever position it is placed, since gravity has nochance to produce motion, thereby providing a pendulum whose point ofsuspension is infinity. l

When it is desired to provide a pendulum whose point of suspension isless than infinity, it will be readily appreciated that this may beaccomplished by increasing the length of G with'relation to F, while, onthe other hand, the opposite effect, that is, an inverted arc,

G with relation to F.

F igure 7 1s a schematic diagram of an 1nby decreasing the length offinity pendulum wherein the lengths of E, F and G are unequal. In thisinstance, the pendulum may be. caused to move in a horizontal line by soproportioning the lengths of F and G with respect to E, as to cause themembers E and F to vary the motion and angle of G in exactly the rightratio to cause B to move in a straight horizontal line. The

relative lengths of E, F and G may be readily ascertained by the simpleequation (E F F: G) or (F /E=G). For example, if the length of E is 4and F is 6", G must bear the same relation to F that F bears to E (1.5to 1) Therefore, G must be 9 in length to cause the pendulum tooscillate in a straight line. It will be readily apparent from thediagram, that any increase in the length of G will cause B to move in.an arcuate path, while any decrease in G will produce an inverted arc.a limit to the distance O may travel without interfering with theprinciples just announced, thatis to say, the distance ()1, rep:resenting the distance between the vertical and O, must not exceed adefinite proportion, ,1.

to wit, the ratio of O to E must be the same as E to For the ratio maybe expressed thus: (0 :E :':E :F) or v(E 1 0 This last rule likewiseapplies to the diagram shown in Figure 6 and, in fact, it will beunderstood that the principles of both diagrams are the same in everyrespect, the diagram of Figure 7 being merely a variation of the simplerFigure 6.

Manifestly, the construction shown and de- I justable thereon to varyits point of suspension.

- '2. A device of the character described comprising a pendulum, apivoted lever supporting said pendulum and oscillating therewith, aguide roller carried on said pendulum and adjustable thereon to vary itspoint of suspension, and .guide rods associated with said roller.

3. A device of the character described comprising a pendulum, a pivotedlever supportin g said pendulum and oscillating therewith, a guideroller carried by said pendulum and adjustable thereon to vary its pointof suspension, a pair of paralleling guide rods associated withsaid'roller, and means to adjust said rods in relation to each other foraccommodating said roller. Y

4. A depice of the character described comprisinga pendulum, anadjustable bob for said pendulum, a pivoted lever supporting It shouldbe noted that there-is said pendulum and oscillating therewith, andmeans carried by the pendulum and adjustable thereon to vary its pointof suspenslon.

5. A device of the character described comprising a pendulum, a pivotedlever supporting said pendulum and oscillating therewith, a yeildingcable, and a clamp connecting said cable to the pendulum and adjustableon the latter to vary its point of suspension.

6. A device of the character described comprising a pendulum, a pivotedlever supporting said pendulum and oscillating therewith, a relativelyshort cable having one end yieldably fixed at a point remote from thependulum, a relatively long cable having one end directly fixed at apoint remote from the pendulum, said latter point being opposed to thefixing point of said relatively short cable, and a clamp connecting thefree ends of said cables to the pendulum, and adjustable on the latterto vary its point of suspension.

7. A device of the character described comprising a pendulum, a pivotedlever supporting said pendulum and oscillating therewith, a sectionalrod having one end fixed at a point remote from the pendulum, and aclamp connecting the other end of said rod,

to the pendulum, and adjustable on the latter to vary its point ofsuspension.

8. A device of the character described comprising a pendulum, a pivotedlever supporting said pendulum and oscillating therewith, a sectionalrod having one end fixed at a point remote from the pendulum, a clampconnecting the free end of said rod to the pendulum and adjustablethereon to vary its length of suspension, and means between thesectional rods to vary the length thereof.

9. An educational device of the character described comprising asupport, a lever, means for pivotally connecting one end of said leverto said support, a pendulum supported by and pivotally connected at apoint intermediate of its length to said lever where by the latter willoscillate therewith, a bob adjustably connected to the lower end of saidpendulum, and means adjustably mounted upon said support and havingconnection with the upper end of said pendulum for varying the latterspoint of suspension.

In witness whereof I have hereunto set my hand.

EIFFEL GRAY PLASTERER.

